A-C

2,3-Diphosphoglycerate

A compound in red blood cells that affects oxygen binding to and release from hemoglobin.

Ablation

Destruction of part or all of an organ or structure.

Abscess

Purulent collection of fluid separated from surrounding tissue by a wall consisting of inflammatory cells and adjacent organs.

Acanthosis nigricans

Increased thickness and hyperpigmentation of the outer cell layers of the skin; typically observed at areas of flexure.

Acaricide

A chemical that kills mites and ticks.

Acetylcholine

Neurotransmitter at synapses in the ganglia of the visceral motor system and a variety of sites within the central nervous system.

Achalasia

Disorder in which the esophageal sphincter is impaired, preventing normal swallowing and often causing reflux of contents and a feeling that something is caught in the throat.

Achlorhydria

Absence of free hydrochloric acid in the stomach.

Acinar cells

Cells in the pancreas responsible for the synthesis, secretion, and storage of certain digestive enzymes.

Action potential

A rapid change in the polarity of the voltage of a cell membrane from negative to positive and back to negative; a wave of electrical discharge that travels across a cell membrane.

Acute coronary syndromes

Ischemic chest discomfort at rest most often accompanied by ST-segment elevation, ST-segment depression, or T-wave inversion on the 12-lead electrocardiogram; caused by plaque rupture and partial or complete occlusion of the coronary artery by thrombus.

Acute respiratory distress syndrome

Diffuse inflammatory condition of the lung resulting in damage of alveoli, surfactant production, innate immune system response, and dysregulation of hemostasis in the pulmonary tract.

Addiction

A primary, chronic, neurobiologic disease characterized by behaviors such as impaired control over substance use, compulsive use, continued use despite harm, and craving.

Adenoma

A non-malignant tumor of the epithelial tissue that is characterized by glandular structures.

Adenomatous polyposis coli

A gene associated with familial adenomatous polyposis, an inherited disorder characterized by the development of myriad polyps in the colon, often occurring in adolescents and young adults ages 15 to 25.

Adjuvant chemotherapy

Treatment given after primary surgical treatment and designed to eliminate any remaining cancer cells that are undetectable, with the goal of improving survival.

Adrenalectomy

Surgical removal of an adrenal gland.

Adverse drug reaction

Any unexpected, unintended, undesired, or excessive response to a medication that requires discontinuing the medication or modifying the dose.

Aeroallergen

Airborne substance that causes an allergic response.

Afterload

The force against which a ventricle contracts that is contributed to by the vascular resistance, especially of the arteries, and by the physical characteristics of the blood.

Ageism

Discrimination against aged persons.

Air embolus

An obstruction in a small blood vessel caused by air that is introduced into a blood vessel and carried through the circulation until it lodges in a smaller vessel.

Akathisia

Motor or subjective feelings of restlessness, often characterized by the urge to move limbs and inability to sit still.

Akinesia

Lack of movement.

Allodynia

Pain that results from a stimulus that does not normally cause pain.

Allogeneic

A transplant taking cells from one person and donating them to another.

Allograft

Tissue or organ transplanted from a donor of the same species but different genetic makeup.

Alopecia

Hair loss.

Amenorrhea

The absence or discontinuation of regular menstrual periods.

Ampulla of Vater

Dilation of the duodenal wall at the opening of the fused pancreatic and common bile ducts.

Amylin

A 37-amino acid polypeptide hormone that is secreted from the β-cells of the pancreas in response to nutrients.

Amyloid

Any of a group of chemically diverse proteins that are composed of linear non-branching aggregated fibrils.

Anaerobic

Living in the absence of oxygen.

Anaphylactic/anaphylaxis

Immediate, severe, potentially fatal hypersensitivity reaction induced by an antigen.

Anaphylactoid

An anaphylactic-like reaction, similar in signs and symptoms but not mediated by IgE.

Anastomosis

The connection of two hollow organs to restore continuity after resection.

Androgen deprivation therapy

Agents used to suppress testosterone levels to that consistent with medical castration.

Aneurysm

A blood-filled bulge which forms in the wall of a weakened blood vessel.

Angioedema

Swelling that occurs beneath the skin instead of on the surface.

Angiogenesis

The formation of new blood vessels.

Anosmia

Loss of smell.

Anovulatory cycle

A menstrual cycle where ovaries fail to produce, mature, or release an egg.

Anterior circulation

Blood supply to the anterior section of the brain supplied by the internal carotid arteries.

Anterograde amnesia

Inability to create new memories or recall the recent past.

Anticoagulant

Any substance that inhibits, suppresses, or delays the formation of blood clots.

Antiprotease

A substance that inhibits the enzymatic activity of a protease.

Aortic dissection

A serious condition in which there is a tear in the wall of the aorta.

Aortic stenosis

A condition in which the aortic valve becomes thickened or calcified leading to a narrowing of the aortic valve opening.

Aphasia

Impairment of language affecting the ability to speak and to understand speech.

Aphthous ulcer

A small superficial area of ulceration within the gastrointestinal mucosa.

Apoptosis

Programmed cell death as signaled by the nuclei in normally functioning cells.

Arcuate scotoma

An arc-shaped area of blindness in the field of vision.

Arteriovenous malformation

A tangle of blood vessels resulting in abnormal connections between arteries and veins.

Arthrocentesis

Puncture and aspiration of a joint.

Articular

Related to the joints of the body.

Ascites

Accumulation of fluid within the peritoneal cavity.

Asterixis

Involuntary jerking movements, especially in the hands.

Astringent

A substance that causes tissues to constrict.

Atelectasis

Decreased or absent air in a partial or entire lung.

Atherosclerosis

Accumulation of lipids, inflammatory cells, and cellular debris in the arterial wall.

Atresia

Congenital absence of a normal opening or normally patent lumen.

Atrophic urethritis

Thinning and inflammation of the vaginal walls experienced by almost 50% of postmenopausal women.

Aura

Visual, but sometimes sensory, motor, or verbal disturbance, usually occurring before a migraine.

Auspitz sign

Pinpoint bleeding that occurs when a psoriasis scale or lesion is peeled off of the skin.

Autologous

A transplant using one’s own stem cells.

Autoreceptor

Transmitter receptors on or near presynaptic terminals which are sensitive to the transmitter(s) released by the terminal itself.

Avolition

Inability to initiate and persist in goal-directed activities.

Azoospermic

Having no living spermatozoa in the semen.

Bacteremia

Presence of bacteria in the blood.

Barium enema

A diagnostic test using an x-ray to view the lower gastrointestinal tract after rectal administration of barium sulfate.

Barrett esophagus

A change of the normal squamous epithelium of the distal esophagus to a metaplastic, columnar-lined epithelium.

Basal ganglia

Cluster of nerve cells deep in the brain that coordinate normal movement.

Bence–Jones proteins

Light chained immunoglobulins found in the urine.

Blood urea nitrogen (BUN)

A waste product in the blood produced from the breakdown of dietary proteins.

Body mass index

A calculation utilized to correct weight changes for height.

Bouchard nodes

Hard, bony enlargement of the proximal interphalangeal joint of a finger or toe.

Boutonniere deformity

Joint deformity associated with rheumatoid arthritis.

Brachial plexus

Collection of nerves that arises from the spine at the base of the neck.

Brachytherapy

A form of radiotherapy where a sealed radiation source is placed inside or next to the area requiring treatment.

Bradycardia

Slower than normal heart rate.

Bronchiectasis

Chronic dilation of bronchi or bronchioles as a result of inflammatory disease or obstruction.

Bullectomy

Surgical removal of one or more bullae in the lung.

Burst suppression

Electroencephalography pattern characterized by electrical brain activity alternating with periods of no activity.

Calcitonin

A hormone produced by the parafollicular cells of the thyroid gland.

Calculi

An abnormal concretion usually found in hollow organs or their passages (e.g., kidney stone).

Capillary leak

Loss of intravascular volume into the interstitial space.

Carcinogenesis

Production or origin of cancer.

Carcinoma

A malignant growth that arises from epithelium.

Carcinomatosis

Condition of having widespread dissemination of carcinoma in the body.

Cardiac cachexia

Physical wasting with loss of weight and muscle mass caused by cardiac disease.

Cardiac index

Cardiac output normalized for body surface area.

Cardiac output

The volume of blood ejected from the left side of the heart per unit of time.

Cardiac remodeling

Genome expression resulting in molecular changes manifested as changes in size, shape, and function of the heart.

Cardiomyopathy

Diseases of the heart muscle where the heart muscle becomes enlarged, thick, or rigid.

Carotid bruit

Abnormal sound heard when auscultating a carotid artery.

Castration resistant prostate cancer

Prostate cancer that continues to progress despite suppression of typical hormonal growth signals.

Cataplexy

A sudden loss of muscle control with retention of clear consciousness that follows a strong emotional stimulus.

Catheterization

Insertion of a tubular medical device into canals, vessels, passageways, or body cavities.

Causalgia

Persistent burning pain following a traumatic nerve lesion.

Cavitary lesions

Gas or fluid filled areas of the lung in the center of a nodule observed through radiographic investigation.